Anybody ever hear an EFI act like this before?

[wrench 3]

Other than running concentrated injector cleaner through the system they'd have to go to a specialty shop. Most fuel injectors have a screen in the fuel inlet but I don't know about yours. You could take a look and maybe get an idea if any thing got to them but they're not usually serviceable.
I'm afraid I can't tell what the contamination is from here.

 

[sutor623]

I'm afraid I can't tell what the contamination is from here.

Me neither!! I am going to pop open the engine mounted fuel water separator that is pre-fuel pump and see what I can. I also want to open up the mechanical fuel pump and see whats going on there. I want to rebuild it but can only find complete fuel pumps. Those diaphrams cant be but a couple bucks.

Only thing I can think about the contamination is water in the gas that made it by the NEVER CHANGED fuel/water filter and when the motor sits between seasons the minerals settle to the bottom of the tank. The debris has the consistency of lime or other hard water contaminants.

 

[sutor623]

Oh and it looks like there is a special tool to remove the injectors from the TFI manifold. Or can you just ease em out by hand?

 

[wrench 3]

The bolt on the fuel line is the only thing that holds the injector in place but the "O" ring in the manifold can get stuck pretty good at times. It just takes a steady pull to get them out.

 

[sutor623]

Vinegar broke the depostis down real good, so I am certain it is mineral deposits from water in the fuel. Cleaned everything up real good. Waiting on parts to get it all back together. Ill let you know how it goes.

Luckily, High Flow Fuel sells aftermarket fuel pumps for $70. If I had to pay $500 for a new Merc fuel pump, Id probably leave this one in there until it croaked. Few reasons I am changing it: the resistance is off spec, I have heard an intermittent whine from the engine and I think its the fuel pump, running against a blocked output like that can't be good for longevity, and lastly, I don't want to have to get back into the VST anytime soon!!!

Cool way that I checked my fuel pressure regulator: I put my air gun to 60 psi and put it into the fuel input side of the regulator. When I let the air go through you could hear the valve squeal off of its seat, and as the pressure dropped down to around 40-45psi the seat closed and air didn't make it past the valve. No reason to spend $150 on a regulator that is working fine!

 

[wrench 3]

Mineral deposits were probably a combination of ethanol fuel and not draining the VST in the off season.

 

[sutor623]

Ok update!!

I cleaned the entire fuel system, and put all new fuel lines on everything. Brand new high pressure fuel pump also. I pulled the injectors just to make sure no sediment made it into the fuel manifold and injectors. Everything looked good and clean in there. This motor will only see E free now, as long as I own it.

Started her up and she ran great. Fuel pressure regulator read 44psi from key on, all the way up to 2000 rpms. That dirty screen was definitely the culprit. I didn't see any shuddering, and I will check back in to confirm after a few trips.

So at this point I'm going to call it good to go!! Thanks so much for the excellent support and daily responses Wrench!!!

 

[wrench 3]

Sounds good.
Happy boating.